Safety relay cut-out for generators



July 15, 1930. J. c. CRONKHITE SAFETY RELAY CUTOUT FOR GENERATORS Filed May 26, 1926 -far Q] Uro khize Patented July 15, 1930 PATENT OFFICE JUSTIN our GRONKHIII, min), OKLAHOIL SAIITY RELAY CUT-OU'IZI'OB GENERATORS Application am: an as, me. Serial n. 111,901.

This invention relates to electrical control apparatus, particularly to that type designed for use in connection with current generators such as are used, for instance, on motor vehicles, and has for its object the provision of a novel safety relay cutout designed to be interposed in circuit with the generator, the

' storage battery, the light of a motor vehicle, or any other devices to be operated, the

1; construction being such that in case the generator is operating on an open circuit the building up of the volta within the'armature of the generator, w ich bulldlng up is bound to occur, will have no bad efi'ect' upon 15 the lightin or ignition system.

It is well known that if the generator is operated on an open circuit which may be caused by a poor connection or a'broken one, the voltage builds up within the armature to 20 a very great extent, frequently as high as fifty volts and it is of course obvious that the headlam s or other electrical devices are bound to be urned out. Furthermore, there is great danger that the armature of the 5 generator itself will burn out, these cond1- tions of course resulting in a great expense inasmuch as repairs to these electrical devices are not easily made and require considerable skill, care and experience, as well as labor. It is to avoid this condition that I have designed the present relay cutout which is so constructed and arranged that under normal conditions current will be supplied from the generator to whatever devices are to be energized, but upon a comparatively slight increase in volta e, means will be operated to ground the eld of the generator so that the generator will become temporarily ineffective and will therefore cease to rmit additional current to build up within its armature.

An important object is to provide a device of this character which embodies various structural features which are characteristic of the invention and which will insure positive and efiicient action as well as durability in service.

An additional object is to provide an apparatus of this character which will be comparatively simple and inexpensive 1n manufacture, entirely automatic in action and a general improvement in the art.

With the above and other objects and advantages in view, the invention consists in the details of construction, and the arrange- 53 ment and combination of elements to be hereinafter more fully described and claimed, and illustrated in the accompanying drawing, in which The figure is an elevation tion, showing the complete device, the electrical connections or circuit diagram being also included.

Referring'more particularly to the drawin I have shown the device as having certam mechanical features, notably a suitable supporting base upon which is carried abracket 11 supporting a member 12 from which rises a supportin post 13 carrying a top plate member 14. O viousl more posts 70 like the one 13 may be provi ed if found necessary or advisable. The post 13 also carries a core 15 on which are wound two coils 16 and 17 the former being a shunt coil and the latter a series coil as will be explained.

Mounted upon one end of the upper plate 14 as by a spring 18 is a depending armature 19 normally spaced from the ad acent end of the core 15 and carrying, at its lower end, a contact point 20 normally engaging a contact point 21 on an arm 22 secured to and insulated from the underside of the lower plate member 12. A slotted guide strip 23 of insulating material may be provided for the armature 19 for limiting its movement or preventing it from having excessive movement. At .its upper end the armature 19 is also e uipped with a spring 24'extending throu a slot in the upturned end 25 of aguidefiiracket 26 on the upper plate14.

Mounted at the other end of the top plate 14 as by a spring 27 is a de ending armature 28 adjacent the other end 0 the core 15. The lower end of the armature 28 carries a contact point 29 cooperating with a contact point 30 on an arm 31 mounted beneath and insulated from the lower plate 12. A slotted guide strip 32 of insulating material may be provided for limiting the movement of the partly in sec- 69 v armature 28'. As in the case of the armature 19, the armature 28 also is provided at its upper end with a spring 33 which passes through the slotted upturned end 34 of a guide bracket 35 on the top plate 14.

The base 10 of course carries suitable binding posts 36, 37 and 38, whereby the necessary electrical connections may be made with a generator A and storage battery B.

The electrical diagram is as follows: As is customary, the generator A includes field coils C and I) connected in series and connected with a brush I which operates on the commutator carried by the armature F. Also cooperating with the commutator are other brushes G and H, the latter of which is grounded in the usual manner. The storage battery B has one terminal grounded. In connecting my safety relay cutout device with the electrical system of the generator and storage battery, the remaining terminal of the field coils C and D which are connected in series is connected by a conductor 39 with the binding post 36 which is in turn connected by a conductor 40 with the member 22 and through the contacts 21 and 20 with the armature 19. It should be stated that the armature 19 and arm member 22 are shunted by a suitable condenser 41 to avoid sparking and burning away of the contact points 20 and 21. The brush G is connected by a conductor 42 with the binding post 37 which connects by a conductor 43 with one terminal of both the shunt coil 16 and the series coil 17. The remaining terminal of the shunt coil is grounded in a convenient manner as for example upon the core 15 while the remaining terminal of the series coil 17 is connected with the guide brackets 35. The positive terminal of the storage battery is connected by a conductor 44 with the binding post 38 which is connected with the arm member 31. The arm tor 40 to the armature 19 and thence through the contact points 20 and 21 to the member 22 which is suitably insulated from the generator frame or car frame. The contact points 20 and 21 are normally in engagement. The operation of the device is as follows:

Assuming that the circuit starts at the brush E, the current passes thru the field coils D and C, thru the conductor 39 to cont-act 36 which is not grounded, from 36 to member 22. which is insulated, thru 22 to points 21 and 20, thru arm 19 and grounded thru screw supporting member 18, and returns to ground brush H. Vhen a circuit in a coil is broken, the reacting voltage is raised above normal, but in automobile ignition and lighting systems the generators are wound in such manner that this will notcause any damage because there are not enough turns of wire in the field coils or armature to produce this effect. The average generator on automobiles operates on six volts and the lights are designed to be energized by a voltage of from six to eight volts and may possibly withstand as much as sixty volts for a short time.

From the foregoing description and a study of the drawings, it will be apparent that I have thus provided a simply constructed and automatically acting relay cutout which will be a great safety device in preventing damage to the generators provided in connection with the electrical systems of motor vehicles or the like. It is really believed that the construction, operation and advantages will be readily apparent to one skilled in the art without further explanation.

While I have shown and described the preferred embodiment of the invention, it should be understood that I reserve the right to make such changes in the form, construction and arrangement. of parts as will not depart from the spirit of the invention or the scope. of the snbjoined claim.

Having thus described the invention, I claim:

The combination with a generator having field coils, and a battery to be charged thereby, said generator and battery each having one terminal grounded and being included within an electrical circuit of a relay cutout including a core, a shunt winding on said core, a series winding on said core, one terminal of the series winding being connected with one terminal of the shunt winding, and circuit makers and breakers including armatures adjacent the ends of the core and carrying contact points. on* armature being connected in series with the field coils of the generator and grounded, the series winding being connected with the other armature, and a stationary contact engageable by the second named armature and connected with the positive terminal of the battery.

In testimony whereof I atlix my signature.

JUSTIN CHET CRONKHITE. 

